Laminated Busbar Surface Treatment Decoded (Part 3): Silver Plating & Composite Coatings

1. Core Functions of Silver Plating

1. Lowest contact resistance & best conductivity

Silver provides the lowest contact resistance and minimal loss at high current & high frequency, making it the top choice for high-end IGBT/SiC busbars.

1. Good temperature resistance

Continuous operating temperature up to 180℃+, better than tin plating.

1. Stable oxidation resistance & lubricity

Silver layer is chemically stable; self-lubricating for smoother assembly and uniform contact.

1. Excellent solderability

Compatible with soldering, brazing, and ultrasonic bonding.

1. No tin whisker risk

Safe for narrow-gap, high-voltage Laminated Busbars.

2. Recommended Process: Electroplated Silver

• Standard: Cyanide-free silver plating (RoHS compliant)
• Features: room temperature, dense coating, precise thickness control
• Forbidden: plating finished assembled busbars

Typical Flow

Copper sheet → Deburr → Electrocleaning → Rinsing → Activation →

Nickel underplate → Rinsing → Silver plating → Rinsing →

Anti-tarnish treatment → Drying → Inspection

3. Thickness Specifications

表格

Must-use: Ni underplate 1–3 μm to prevent silver migration & copper diffusion.

4. Pros & Cons of Silver Plating

Advantages

• Best electrical & thermal conductivity
• Extremely low contact resistance & low temperature rise
• Heat resistance up to 180℃
• Good solderability, compression wear-resistant
• No whiskers; ideal for high-frequency & narrow-gap designs

Disadvantages

• Highest cost
• May tarnish (sulfidation; cosmetic only)
• Silver migration risk in high humidity/high voltage

5. Composite Coatings (Premium Standard)

① Ni + Ag

• Benefits: prevents Cu diffusion, stops Ag migration, strong adhesion
• Applications: EV inverter, ESS PCS, SiC modules, military

② Ni + Sn

• Benefits: 100% tin-whisker free, better corrosion resistance
• Applications: high-reliability automotive & industrial

③ Ni + Ag + Sn

• Balances low resistance and solderability for special bonding needs

6. Laminated Busbar Design Rules

1. Plate first, laminate later

Single sheet plating → Forming → Hot-press lamination.

1. Always use nickel underplate

1–3 μm Ni before Ag/Sn for reliability.

1. Selective plating only

Plate conductive & contact areas; avoid bonding surfaces.

1. Silver migration control

Increase creepage distance, full insulation, conformal coating.

1. Anti-tarnish for silver

Passivation or organic protection to prevent tarnish.

7. Final Comparison

表格

8. Quick Selection Guide

• Cost-effective, general use → Tin plating
• High temperature, zero whiskers → Ni plating / Ni+Sn
• High current, high frequency, premium → Ag plating / Ni+Ag
• 🌟 About A&J Link
• A&J Link specializes in the design, manufacturing, and technical services of laminated busbars. With independent innovation as the core, we provide customized power interconnection solutions for global customers.
• Making Power Transmission More Reliable, Efficient, and High-Temperature Resistant